F.A.C.T.

Lie Detectors – Friend or Foe ?
An article by Trevor Jones from our ‘In my opinion’ series Earlier this year the Home Secretary, John Reid, took the first step towards introducing compulsory lie detector tests for paedophiles to assess whether they are at risk of reoffending. Such action may have comforted the readers of the Sunday tabloids but it has also provoked debate amongst F.A.C.T. members with many seeing it as an opportunity to press for the use of lie detectors in the cases of those falsely accused, not only to bolster a defence by passing a polygraph test, but by pressing accusers to take the tests as well. A refusal to take part in such tests by an accuser would speak volumes for the veracity of the witness statements whilst the accused, in passing the test, would see it as useful in seeking to place it in front of a jury. On paper, the argument for using polygraph testing to assist those falsely accused certainly has its merits, so should we have reservations? The lie detector or polygraph, despite its name, does not actually detect lies but measures reactions. A subject’s heart beat, breathing rate, blood pressure and sweating are all measured whilst he or she is asked a series of questions. The accuracy or validity rates in polygraph testing can be highly variable across situations. They can range from over 90% to as low as 60%, which is not much better than tossing a coin. Daniel Sosnowski, a former US police officer and leading light in the American Polygraph Association, has advised the Home Office in its recent study on the use of polygraph testing on sex offenders and believes they are 90% accurate but a major survey of 421 psychologists in 1997, published in the Journal of Applied Psychology, estimated the average validity rate to be about 61%. The average rate appears to be in the range of 70%-80% suggesting that one person in four telling the truth will be shown up by the test as having lied. To be wrongly accused once by a person is traumatic enough but to be wrongly accused a second time – and by a machine – could be devastating to anyone living the nightmare of being accused of child abuse. So why are lie detectors inaccurate? As a polygraph machine simply measures physiological reactions to questions, it is not only deception that will drive a response but fear, revulsion, anger, disbelief or any other emotion. The machine may well be detecting sheer nervousness and nobody really knows how the nervous system acts when it is lying or telling the truth. Indeed, falsely accused teachers and carers may be more inclined to fail these tests as they are more sensitive than the general population, and given the sexual nature of the accusation a certain amount of revulsion may be generated within caring, responsible people thus creating the physiological response that can be interpreted as ‘lying.’ Neither the scientific nor legal community has sat back and allowed polygraph testing to escape scrutiny.

The late Professor David Lykken who was regarded by many as the world’s leading expert on the polygraph finally debunked it, “as much of a myth as the tooth fairy” in his book “Tremor in the Blood: Uses and Abuses of the Lie Detector”, whilst the US Supreme Court in 1998 observed that “there is simply no consensus that polygraph evidence is reliable.” However, by far the most significant scientific finding on the polygraph did not appear until 2003 when the US National Academy of Sciences completed a major review of its validity and concluded that “the theoretical rationale for the polygraph is quite weak, especially in terms of differential fear, arousal and other emotional states that are triggered in response to relevant or comparison questions.” The venerable scientific body went on to state that “there is essentially no evidence on the incremental validity of polygraph testing, that is, its ability to add predictive value to that which can be achieved by other methods.” The most comprehensive study yet on the subject therefore found that polygraphs are inaccurate, scientifically unsubstantiated, easily foiled, of no proven value and can snare the innocent while missing the guilty. Those backing the Home Office initiative into the use of lie detectors admit that there are concerns over their accuracy and it is important to realise that the plan is to use polygraph testing as a tool to control sex offenders and not as an investigative tool. The rationale behind the programme is that it has been shown to be an effective way to monitor paedophiles and can therefore encourage offenders to disclose information which will be useful to protect children. Polygraph testing has run its course in the USA and has been found wanting, resulting in some government departments ending compulsory testing for employees and many states and federal courts banning polygraph testing outright. Perhaps then it is not surprising that it is being slowly introduced into Blair’s Britain having passed its first test – daytime British TV talk shows. For those wrongly accused of abuse it will only offer false hope as in its present form there will be no possibility that it will be accepted as evidence in a British court and for those 25%-30% who will be false positives in being told they were lying when they were telling the truth it will be devastating to them and their families. Polygraph testing was developed in the 1930s from an idea by William Marston, the creator of the comic book figure, Wonder Woman. There are many who believe that is where the lie detector should return to – the world of fantasy. Trevor Jones April 2007 The F.A.C.T. national committee recently discussed what its stance should be on the use of lie detectors. We are aware for example that some F.A.C.T. members have commissioned lie detectors tests for use as part of their defence in criminal proceedings but were prevented from placing the results before a jury for legal reasons. We are also mindful of the fact that many of those accused of abuse young people in child care institutions in Nova Scotia, Canada (see FACTion Vols 3 /3 & 3/4) used polygraph testing to their advantage, but found it to be a very distressing and intrusive experience.